1. Field of the Invention
The present invention relates to a polyphonic electronic music system which provides output tone signals that can be either musically independent or in combination with conventional organ accompaniment, or the system can provide the background or accompaniment to conventional organ solo voices. The present invention further relates to techniques for producing orchestral chord tone signals that are slightly detuned to provide a fuller, richer more realistic ensemble effect.
2. Description of the Prior Art
Upon activation of a single key, it is old in the organ art to produce simultaneously, by stop selection, tones of different timbre and the same pitch, or by coupler selection, different octavely or harmonically related frequencies in the same timbres, or both of these at the same time.
It is also old for keys of different notes played simultaneously on different manuals of an organ to produce different timbres depending upon the particular stops selected on the different manuals.
Furthermore various key-switching circuits have been devised to associate the frequency of a tone oscillator with the highest or the lowest key played. For example in U.S. Pat. No. 3,801,721 -- Bunger discloses a circuit arrangement for assigning position priority to the highest pitch key of a set of actuated keys. Dual oscillator key-switching systems have been designed to respond to the highest and the lowest keys played. However, when the position priority key-switching methods are extended to larger numbers of notes played, the switching becomes very cumbersome both mechanically and electrically.
Various multiplexing techniques have been used to reduce the wiring complexity between the playing key switches and the gating circuits which control the flow of tone signals. Examples include U.S. Pat. Nos. 3,746,773 -- Uetrecht and 3,916,750 -- Uetrecht. Time priority systems have also been devised for assigning a plurality of tone frequency means to keys in the order in which they are played in time as in U.S. Pat. No. 3,610,799 -- Watson. However, the individual tones of chord notes played on the same keyboard or manual have generally been heard in the same timbre or timbres in contrast to the present invention. It is believed to be a unique advance in the art to provide a polyphonic electronic music system capable of automatically providing orchestral chord tonal outputs with different voices for different notes in a complex chord, and of automatic doubling of different voices on the same note when the chord becomes less complex in order to continue the ensemble effect.